Organic light-emitting diode (OLED) devices, also referred to as organic electroluminescent (EL) devices, have numerous well known advantages over other flat-panel display devices currently in the market place. Applications of OLED devices include active matrix image displays, passive matrix image displays, etc. Without considering particular OLED device configurations tailored to these broad fields of applications, all OLEDs function on the same general principles. An organic electroluminescent (EL) medium structure is sandwiched between two electrodes. In general, one of those two electrodes is light transmissive. When an electric potential is applied between the electrodes so that the anode is connected to the positive terminal of a voltage source and the cathode is connected to the negative terminal thereof, positive charge carriers (holes) are injected from the anode into the organic EL medium structure, and negative charge carriers (electrons) are injected from the cathode. Such charge carrier injection causes current to flow from the electrodes through the organic EL medium structure. Recombination of holes and electrons within a zone of the EL medium structure results in emission of light from this zone.
OLED devices have advantages of self-luminescence, wide viewing angle, high response speed, good color saturation and smooth appearance, etc. Despite their advantages, unprotected OLED display devices are prone to rapid degradation of performance due to adverse effects of oxygen and/or moisture present in the ambient environment. So far, there are two methods for overcoming the effects. One is to form a protective layer on the outer surface of the OLED by using a deposition method for avoiding oxygen or moisture infiltration, and the other is to provide a getter to the OLED for adsorbing moisture. However, these methods can cause additional processes and production cost, and can even reduce the luminous efficiency due to the shielding effect of the protective layer. Therefore, there may be issues of moisture infiltration and incompatibility with some OLEDs.
Thus, it is desired to have an organic light-emitting device which can reduce the moisture infiltration without implementing additional processes.